KR102591838B1 - Flexible printed circuit board, manufacturing method therefor, and cladding sensor module thereof - Google Patents

Abstract

A flexible printed circuit board having heat resistance and strength equivalent to or higher than that of PEN film by coating liquid PI on at least one side of a PET film substrate and a method for manufacturing the same are presented. The presented flexible printed circuit board and its manufacturing method include a base film made of polyethylene terephthalate (PET), a base substrate including a first coating layer located on one side of the base film and made of polyimide (PI), and a first coating layer of the base substrate. It is laminated on the coating layer and includes a metal layer selected from copper and aluminum.

Description

Flexible printed circuit board, manufacturing method thereof, and vehicle cladding sensor module using the same {FLEXIBLE PRINTED CIRCUIT BOARD, MANUFACTURING METHOD THEREFOR, AND CLADDING SENSOR MODULE THEREOF}

The present invention relates to a flexible printed circuit board, and more specifically, to a flexible printed circuit board that can be used in a cladding sensor installed in a vehicle, an advanced driver assistance system (ADAS), etc., and a method of manufacturing the same.

Vehicles are exposed to harsh environments due to various weather conditions, temperature changes, moisture ingress, etc. Electronic devices installed in vehicles must be able to be used in harsh environments.

Accordingly, electronic devices installed in vehicles use flexible printed circuit boards made of PEN (Polyethylene Naphthalene) film, which has excellent heat resistance and strength.

However, PEN film has the problem of making it difficult to manufacture large FPCBs due to limitations in the manufacturing process. In other words, there is a problem in that it is difficult to manufacture large FPCBs with a length of 1000 mm or more used in automotive devices.

In addition, PEN film is more expensive than PET (polyethylene terephthalate) film, which is mainly used in general environments, so there is a problem in that the product cost of flexible printed circuit boards increases.

Korean Patent Publication No. 10-2016-0111587 (Name: Heat dissipation type flexible copper clad laminate, heat dissipation type flexible printed circuit board and manufacturing method thereof)

The present invention was proposed to solve the above-described conventional problems, and provides a flexible printed circuit board having heat resistance and strength equivalent to or higher than that of a PEN film by coating liquid PI on at least one side of a PET film substrate, and a method for manufacturing the same. The purpose.

In order to achieve the above object, the flexible printed circuit board according to the first embodiment of the present invention includes a base film made of polyethylene terephthalate (PET), a first film located on one side of the base film, and made of polyimide (PI). It is laminated on a base substrate including a coating layer and a first coating layer of the base substrate, and includes a metal layer selected from copper and aluminum.

At this time, the flexible printed circuit board according to the first embodiment of the present invention further includes an adhesive layer disposed between the base substrate and the metal layer, and a second coating layer disposed on the other side of the base film from the base substrate and made of polyimide (PI). can do.

In order to achieve the above object, the flexible printed circuit board according to the second embodiment of the present invention has a circuit pattern in which a coating layer is formed on one side of a base film, which is a polyethylene terephthalate (PET) film, and a metal layer is formed on the other side of the base film. It is located on top of the metal layer of the substrate and circuit pattern substrate, and includes a coverlay substrate with a coating layer formed on both sides of a base film that is a polyethylene terephthalate (PET) film. At this time, the coverlay substrate may be adhered to the upper surface of the metal layer of the circuit pattern substrate with an adhesive layer.

In order to achieve the above object, a method for manufacturing a flexible printed circuit board according to an embodiment of the present invention includes manufacturing a base substrate through a roll-to-roll process and forming a metal layer on at least one surface of the base substrate, The step of manufacturing the base substrate includes applying a coating solution made of a liquid polyimide (PI) material to one side of a base film, which is a polyethylene terephthalate (PET) film, and curing the coating solution to form a coating layer. At this time, forming the metal layer may include forming an adhesive layer on one side of the base substrate where the coating layer is formed, and placing a metal film on one side of the adhesive layer and then pressing it.

In order to achieve the above object, the cladding sensor module according to an embodiment of the present invention is a cladding sensor module that is installed at one end of a vehicle door and detects an object in the door opening/closing area, including a ground substrate having a first opening, 1, a foam sheet member having a second opening disposed at a position corresponding to the opening, and a foam sheet member disposed spaced apart from the ground substrate with the foam sheet member in between, and disposed at a position corresponding to the first and second openings, and forming the first and second openings. 2 It includes a sensor circuit board including a control unit exposed through the opening and at least one sensor unit formed of a circuit pattern electrically connected to the control unit to detect an object, and the ground board and the sensor circuit board are made of polyethylene terephthalate ( A base material including a base film made of PET), a first coating layer located on one side of the base film and made of polyimide (PI), and a metal layer selected from copper and aluminum, which are laminated on the first coating layer of the base material. Includes.

According to the present invention, the flexible printed circuit board and its manufacturing method have the effect of realizing heat resistance and strength equivalent to or higher than that of the PEN film by coating liquid PI on at least one side of the PET film substrate and forming a metal layer.

In addition, the flexible printed circuit board and its manufacturing method include coating liquid PI on at least one side of a PET film substrate and forming a metal layer, thereby lowering the product price compared to a conventional flexible printed circuit board using a PEN film, and having equivalent or better heat resistance and It has the effect of realizing strength.

Using such a flexible printed circuit board has superior thermal characteristics compared to flexible printed circuit boards using existing PET materials, and can improve the reliability of parts installed in areas with severe temperature changes, such as cladding sensors for vehicles.

1 and 2 are diagrams for explaining a flexible printed circuit board according to a first embodiment of the present invention.
Figure 3 is a diagram for explaining a flexible printed circuit board according to a second embodiment of the present invention.
Figure 4 is a diagram for explaining a method of manufacturing a printed circuit board according to an embodiment of the present invention.
FIG. 5 is a diagram for explaining the metal layer forming step of FIG. 4.
6 and 7 are diagrams for explaining an application example of a printed circuit board according to an embodiment of the present invention.

Hereinafter, in order to explain in detail enough to enable those skilled in the art of the present invention to easily implement the technical idea of the present invention, the most preferred embodiments of the present invention will be described with reference to the accompanying drawings. . First, when adding reference numerals to components in each drawing, it should be noted that identical components are given the same reference numerals as much as possible even if they are shown in different drawings. Additionally, in describing the present invention, if it is determined that a detailed description of a related known configuration or function may obscure the gist of the present invention, the detailed description will be omitted.

Referring to FIG. 1, the flexible printed circuit board according to the first embodiment of the present invention includes a base substrate 100 and a metal layer 200 formed on one surface of the base substrate 100.

The base substrate 100 includes a base film 120, a first coating layer 140 formed on the upper surface of the base film 120, and a second coating layer 160 formed on the lower surface of the base film 120.

The base film 120 is made of PET film, which is relatively cheaper than PEN film. At this time, the base film 120 is formed to have a thickness of approximately 50㎛ to 75㎛.

The first coating layer 140 is formed by coating the coating liquid 180 on the upper surface of the base film 120. At this time, for example, the coating liquid 180 is liquid PI (Polyimide), and after coating the coating liquid 180 on the upper surface of the base film 120, it is cured as heat is applied to form the first coating layer 140. do. Here, the first coating layer 140 is formed to have a thickness of approximately 6㎛ or less.

The second coating layer 160 is formed by coating the lower surface of the base film 120 with the coating solution 180. At this time, the coating liquid 180 is liquid PI (Polyimide) as an example. After coating the coating liquid 180 on the lower surface of the base film 120, it is cured as heat is applied to form the second coating layer 160. do. Here, the second coating layer 160 is formed to have a thickness of approximately 6㎛ or less.

Here, the base substrate 100 has been described as including both the first coating layer 140 and the second coating layer 160 in the base film 120, but is not limited thereto, and as shown in FIG. 2, the first coating layer It may include only one selected from 140 and the second coating layer 160.

Through this, the base substrate 100 is formed of PICF (PI coating on PET film) in which liquid PI is coated on a PET film. At this time, the PI forming the first coating layer 140 and the second coating layer 160 is a high heat-resistant resin with a high melting point, so parts made of PICF have the property of being able to withstand long-term use from extremely low to high temperatures.

In addition, PICF has excellent mechanical strength, electrical properties, chemical resistance, insulation, and radiation resistance, so it can be used in various forms such as molding materials, composite materials, and films.

The metal layer 200 is formed on one side of the base substrate 100. The metal layer 200 is a layer that forms a circuit pattern or an electrode, and may be formed by stacking a metal film on the first coating layer 140 formed on one side of the base substrate 100. At this time, the metal layer 200 is, for example, a copper (Cu) film or an aluminum (AL) film, and is formed to a thickness of approximately 35 μm or less.

Meanwhile, an adhesive layer 300 is interposed between the base substrate 100 and the metal layer 200, so that the base substrate 100 and the metal layer 200 can be adhered. However, this is not limited, and any material that can bond the base substrate 100, which is made of resin, and the metal layer 200, which is made of metal, may be used. The adhesive layer 300 is formed to a thickness of approximately 20㎛ or less and has an adhesive force of approximately 1.1kgf/cm.

Referring to Figure 3, the flexible printed circuit board according to the second embodiment of the present invention may be composed of a circuit pattern substrate and a coverlay substrate.

As an example, the circuit pattern substrate is a flexible printed circuit board according to the first embodiment described above. That is, the circuit pattern substrate is a base substrate 100 coated with one of the first and second coating layers 140 and 160 selected on one surface of the base film 120, and the first and second coating layers in the base substrate 100. One of the coating layers 140 and 160 may include a metal layer 200 adhered to the opposite side of the coated surface through an adhesive layer 300. At this time, the base film 120 is a black PET film, the first or second coating layers 140 and 160 are PI coating layers, and the metal layer 200 is a copper (Cu) foil. Here, in FIG. 3, it is shown that the first or second coating layers 140 and 160 are formed on only one side of the base film 120, but this is not limited to this and the first and second coating layers 140 are formed on both sides of the base film 120. , 160) may be formed.

The coverlay substrate is a base substrate 100 on which first and second coating layers 140 and 160 are formed on both sides of the base film 120, and an adhesive layer ( 300) and a release paper (400; Liner) removably adhered to the adhesive layer 300. At this time, for example, the base film 120 is a black PET film, and the first and second coating layers 140 and 160 are PI coating layers. Here, in FIG. 3, it is shown that the first and second coating layers 140 and 160 are formed on both sides of the base film 120, but this is not limited to this and the first or second coating layers 140 and 160 are formed on the base film ( 120) may be formed on one side.

The coverlay substrate is adhered to the top of the circuit pattern substrate. That is, the coverlay substrate is adhered to the upper surface of the metal layer 200 of the circuit pattern substrate after removing the release paper 400 to expose the adhesive layer 300.

Referring to Figure 4, the flexible printed circuit board manufacturing method according to an embodiment of the present invention manufactures a flexible printed circuit board through a roll-to-roll process, including the base substrate 100 manufacturing step (S100) and the metal layer 200 forming. Includes step S200.

In the step (S100) of manufacturing the base substrate 100, the base film roll 520 on which the base film 120 (i.e., PET film) is wound is placed, and then the base film 120 is transferred to the winding roll 540. .

In the step (S100) of manufacturing the base substrate 100, the coating liquid 180 is sprayed on one side of the base film 120 to be transferred to form a coating layer.

In the step (S100) of manufacturing the base substrate 100, heat is applied through the heater 600 to cure the coating liquid 180 coated on the base film 120 to form the first coating layer 140, and then a winding roll ( 540).

At this time, in the step (S100) of manufacturing the base substrate 100, when forming the first and second coating layers 140 and 160 on both sides of the base film 120, the above-described process is repeated to form the base film 120. A second coating layer 160 may be formed on the other surface.

Here, in the step (S100) of manufacturing the base substrate 100, the coating liquid 180 may be coated on both sides of the base film 120 and then heated to form the first and second coating layers 140 and 160 at the same time. .

In the metal layer 200 forming step (S200), the metal layer 200 is formed on at least one surface of the base substrate 100. That is, in the metal layer 200 forming step (S200), the adhesive layer 300 is formed on one surface of the base substrate 100 where the first or second coating layers 140 and 160 are formed, and a metal film is formed on the upper surface of the adhesive layer 300. The metal layer 200 may be formed by placing and pressurizing.

Meanwhile, referring to FIG. 5, in the step of forming the metal layer 200 (S200), the metal foil 220 wound on the roll 560 is attached to the base substrate 100 after the step of manufacturing the base substrate 100 (S100). The metal layer 200 may be formed on the surface of the base substrate 100 by applying pressure to the metal foil 220 disposed on one side of the base substrate 100 through the rolling roll 580. .

At this time, in the metal layer 200 forming step (S200), an adhesive sheet is interposed between the base substrate 100 and the metal foil 220 on which the first and second coating layers 140 and 160 are formed, thereby bonding the base substrate 100 and the metal. The metal layer 200 is formed by pressing/adhering the foil 220.

The flexible printed circuit board formed as described above can be used for various purposes. As an example, referring to FIGS. 6 and 7, it may be applied to the cladding sensor module 700 of a vehicle.

The cladding sensor module 700 is a sensor that detects objects to prevent accidents when opening and closing a vehicle door, and is mainly mounted on the outside of the door. The flexible printed circuit board may include a ground board 720 of the cladding sensor 700, a foam sheet member 740, and a sensor circuit board 760.

The ground substrate 720 may include a first opening 721 and at least one ground terminal.

The foam sheet member 740 is disposed to space the space between the ground board 720 and the sensor circuit board 760, which will be described later, to insulate them from each other. At this time, a second opening 741 may be disposed in a corresponding shape at a position corresponding to the first opening 721 of the foam sheet member 740.

The sensor circuit board 760 may include a control unit 761 and at least one sensor unit 762.

The control unit 761 may be disposed at a position corresponding to the first and second openings 721 and 741 and exposed by the first and second openings 721 and 741. Since the control components constituting the control unit 761 are formed of EMC (Epoxy Molding Compound) element components, they may have a height of several millimeters or more.

Therefore, when the ground substrate 720 and the foam sheet member 740 are arranged to pass through the first and second openings 721 and 741, the ground substrate 720, the foam sheet member 740, and the sensor circuit are maintained without lifting. It is possible to assemble the substrate 760.

Additionally, the sensor unit 762 may be formed in a circuit pattern that is electrically connected to the control unit 761, and a plurality of sensor units 762 may be arranged symmetrically. The sensor unit 762 can be used as a sensor that detects an object with the pattern itself, or can also be used as a terminal for electrical connection to a separate sensor member.

Meanwhile, the ground substrate 720 and the sensor circuit board 760 are located on a base film 120 made of polyethylene terephthalate (PET) and on one side of the base film 120, as shown in FIGS. 1 to 3. , It may include coating layers 140 and 160 made of polyimide (PI), and a metal layer 200 disposed on one side of the base film 120 where the coating layers 140 and 160 are formed. At this time, the metal layer 200 is laminated on the coating layers 140 and 160, and may be one selected from copper or aluminum.

As mentioned above, when a flexible printed circuit board using a base material with a coating layer of PI material is used, the thermal characteristics are superior to those of a flexible printed circuit board using the existing PET material, so it can be used in areas with severe temperature changes, such as cladding sensors for vehicles. The reliability of parts mounted on a part can be improved.

Although the preferred embodiment according to the present invention has been described above, it can be modified into various forms, and those skilled in the art can make various variations and modifications without departing from the scope of the patent claims of the present invention. It is understood that it can be implemented.

100: base material 120: base film
140: first coating layer 160: second coating layer
180: coating liquid 200: metal layer
220: metal foil 300: adhesive layer

Claims (8)

delete delete delete delete delete delete delete In the cladding sensor module installed at one end of the vehicle door and detecting objects in the door opening and closing area,
A ground substrate having a first opening;
a foam sheet member having a second opening disposed at a position corresponding to the first opening and being stacked on a lower portion of the ground substrate; and
A sensor circuit board laminated on the lower part of the foam sheet member, comprising a control unit disposed at a position corresponding to the first and second openings and passing through the first and second openings, and electrically connected to the control unit. It includes a sensor circuit board including at least one sensor unit formed in a circuit pattern to detect an object,
The ground board and the sensor circuit board are,
A base material including a base film made of polyethylene terephthalate (PET) and a first coating layer located on one side of the base film and made of polyimide (PI); and
A cladding sensor module laminated on the first coating layer of the base substrate and including a metal layer selected from copper and aluminum.